It probably dissolved off screen afterwards.
I don't think it was a great move to introduce Stannis in the second season, by the way. Not sure if that's how it happened in the books, but I get the feeling that he's set up to be a major player. Which begs the question why we've never even heard of him before Joffrey took the throne. He just pops up, knocks up a witch and disappears for five episodes again. He's been on the screen for less than ten minutes this season. I'm not sure exactly who he's related to or how, and I'm not sure I give a fuck either.